Hang test question

Russ Hobbs

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Apr 16, 2008
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Cle Elum, WA
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Dominator Ultra white
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I did a hang test on an ultra white 503, I have a problem but I'm at a loss to know why.

I get 4 on the mast and 15 on the keel with 5 gallons of fuel. (standard 7 gallon seat tank) nuetral stick with me sitting in the machine 2' off the ground.

Empty, I get get 3 on the mast and 13 on the keel. Pretty much the same with 1 gallon of fuel (reserve)

On the ground I got 3.5 on the keel and 12.5 on the mast or 8-8.5 degrees, it should be 9 degrees.

I used a degree scale used in construction, it is new and checks out when placed on an upright framing stud in the hanger.

The tires are all at 30 psi and the gyro was level side to side when I checked it on the ground

The machine is completely stock, built from a RFD kit.

Russ
 
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helipaddy

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I seem to remember that I found that stick movement during the hang test would cause a few degrees error. are you holding the stick during tests or using wedges in the head? check the torque on all bolts from head to keel. After that ,I dunno
 

giro5

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Russ, my dominator is resting on the front and rear wheel only right now. The mast measures 15 deg and the keel measures 6.9 deg or very nearly 7. The difference is very close to 8 deg. This plane was built by RFD. The measuring tool was probably just like you used. This measurement is only useful to show the mast to keel angle. I have no idea of the required hang test numbers.
 

Bob Gregory

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Springfield, MO
Russ Hobbs writes.............
On the ground I got 3.5 on the keel and 12.5 on the mast or 8-8.5 degrees, it should be 9 degrees.
RH


12.5 minus 3.5 is 9.
With your keel at 3.5 degrees.............your take off will be similar to Billygyro's wheel barrow take off described in a recent post.

Here is a picture of a pusher design with the nose wheel at 2 degrees to allow safety from wheel barrowing.
BG
 

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jcarleto

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Russ Hobbs said:
I get 4 on the mast and 15 on the keel with 5 gallons of fuel. (standard 7 gallon seat tank) nuetral stick with me sitting in the machine 2' off the ground.

Empty, I get get 3 on the mast and 13 on the keel. Pretty much the same with 1 gallon of fuel (reserve)
OK..based just on the above, I'd say you need to block/wedge your torque tube rather than trying to hold it in the center. Consider the following:

15 - 4 (full fuel test) = 11 The mast angle is at 11 degrees from the keel.
13 - 3 (empty test) = 10 The mast angle is at 10 degrees from the keel.

Either you have a really "bendy" machine or you aren't holding the stick exactly in the center consistantly. I'm betting on stick movement. It doesn't take much. The key to this stuff is to take your time and eliminate variables. Wedge your torque tube in the center and measure again.

There is always the chance your angle-finder is inaccurate as well. Check it against a good one....or take it into the local hardware store and verify it against a new one.
 

Russ Hobbs

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Apr 16, 2008
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Cle Elum, WA
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Dominator Ultra white
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Thank you, I will take You're advice and try it again, and double check the angle finder.
Russ
 

MikeBoyette

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Russ,
Is this the UW that was for sale there in Washington? If it is it used to belong to Bart Hutchinson and was built by dad. As dad told you yesterday unless someone did some major modification it should be fine. The type of device you are using is notoriusly inaccurate. You should find a smart level if you need to verify it. The samrt level is no longer available new but can sometimes be found on e-bay used. IF you have a camera phone send me a picture via a sms text and I can tell you if it is factory built and not modified. My cell phone number is 813-802-8031.
 

Russ Hobbs

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Cle Elum, WA
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Hi Mike

I sent your dad an email with all the information, I know he doesn't always check his email and I was in class all week, so I thought I'd ask here. Thank you for the information on the previous owner, Ron thought Bart may have been the original owner as well. The Ultra white is stock built, I can't see any alterations or changes. I weigh 165-170, I was told the previous owner weighed about 225. Your dad told me I should just fly it, but that was before I gave him the hang test readings. I'm pretty sure I'm OK, but I'll follow through with another hang test if I can find a smart level.

Thanks again, Russ
 
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